emitWithAck does not throw on disconnect

[jd1378]

Describe the bug
Take the following steps:

• put browser into offline mode
• use emitWithAck to send a message immediately
• expect emitWithAck to throw on disconnect, but it does not
• put browser into online mode and reconnect.
• emitWithAck still not resolving.

To Reproduce

Socket.IO client and server version: 4.7.4

I used the socket.io chat example to make a reproduction repo:
https://github.com/jd1378/socketio-emit-ack-bug

Expected behavior

I expect the emitWithAck to throw once the socket is disconnected. OR, I expect emitWithAck to retry the request, as it's not volatile.

Platform:

• Windows 10, Edge browser

Additional context

What's even better than the expected behavior? a new option to control the behavior.

what I really want is to be able to detect the failure of my requests and throw, much like how a fetch request would throw if connection fails. and I don't want to retry the request automatically when it's thrown.

[darrachequesne]

I could indeed reproduce, thanks for the test case. I'm digging into this.

Related: socketio/socket.io-client#1546

[darrachequesne]

This should be fixed by socketio/socket.io-client@34cbfbb, included in version 4.7.5.

@jd1378 could you please check?

[jd1378]

Hi
I can confirm this is now working as expected by testing again using the reproduction repo
thanks a lot!

[wilywork]

hi @darrachequesne , this line is really necessary?
socketio/socket.io-client@34cbfbb#diff-f0e64910289a49966c99ceadaa5637404e3439ec0812a4bdb7003fe1e5a33d1cR693

If there is an active ack regardless of whether it has a timeout or not, it should be rejected, correct? because in the current situation the ack's registered by the .emit end up being pending

[darrachequesne]

@wilywork hi! Yes, I think this is necessary, as the callback does not expect an Error argument:

socket.emit("hello", (returnValue) => {
  // 'returnValue' would be an Error object, which is unexpected
});

What do you think?